1. Field of the Invention
The present invention is related to an electronic musical instrument having a voltage-controlled oscillator that works as a tone generator, and more specifically to an improved pitch bend apparatus provided with a variable resistor for operating the pitch bend as well as another variable resistor for variably setting the varying width of the pitch bend.
2. Prior Art
Electronic musical instruments such as music synthesizers are, usually, so constructed as to synthesize a musical tone signal of a pitch corresponding to a depressed key by controlling a voltage-controlled oscillator as a tone generator with a pitch voltage which is differently determined for each of the keys. The electronic musical instruments of this sort have so far been equipped with a pitch bend apparatus which allows the pitch to be increased or decreased when a pitch bend operator (usually, a slider of a variable resistor) is moved toward the plus side or the minus side with a key being maintained depressed.
However, with the conventional pitch bend apparatus having a pitch bend operator only as an operating means, it was not allowed to control the varying width of the pitch bend from the external side. That is, the maximum amount of pitch deviation in the upper and lower directions had been fixed to, for example, .+-.1200 cents (equivalent to one octave). With such a pitch bend apparatus, therefore, when it was intended to deviate the pitch by, for example, .+-.500 cents during the play, the pitch bend operator must be so operated that it was stopped at suitable position within the variable range. In practice, however, such an operation was very difficult making it impossible to repeat the play with accurate reproduceability.